<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    * {
        margin: 0;
        padding: 0;
    }

    #outer {
        width: 300px;
        height: 300px;
        margin: 0 auto;
    }

    #tips {
        color: red;
        font-size: 12px;
        width: 160px;
        height: 50px;
        border: 1px solid rgb(235, 155, 90);
        background: yellow;
        display: none;
    }
</style>

<body>
    <div id="outer">
        <label><input type="checkbox">两周内自动登录</label>

        <div id="tips">
            为了您的信息完全，请不要在网吧和公用电脑上使用此功能
        </div>
    </div>

</body>
<script type="text/javascript">
    var yTip = document.getElementById("tips")

    var yLabel = document.getElementsByTagName("label")[0];

    yLabel.onmouseover = function () {
        yTip.style.display = "block"
    };
    yLabel.onmouseout = function () {
        yTip.style.display = "none"
    }
</script>

</html>